US4439664A - Welding apparatus wherein physical contact of welding electrode with workpiece is mechanically sensed - Google Patents
Welding apparatus wherein physical contact of welding electrode with workpiece is mechanically sensed Download PDFInfo
- Publication number
- US4439664A US4439664A US06/372,193 US37219382A US4439664A US 4439664 A US4439664 A US 4439664A US 37219382 A US37219382 A US 37219382A US 4439664 A US4439664 A US 4439664A
- Authority
- US
- United States
- Prior art keywords
- lead screw
- electrode
- bearing
- work surface
- housing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/06—Arrangements or circuits for starting the arc, e.g. by generating ignition voltage, or for stabilising the arc
- B23K9/073—Stabilising the arc
- B23K9/0735—Stabilising of the arc length
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/24—Features related to electrodes
- B23K9/28—Supporting devices for electrodes
- B23K9/287—Supporting devices for electrode holders
Definitions
- the present invention is directed to an arc welding apparatus. More particularly, the present invention is directed to an improved arc welding apparatus wherein physical contact of a welding electrode with a work surface is mechanically sensed, and the electrode is carried to a predetermined distance away from the work surface after the physical contact is made.
- Arc welding apparatus are well known in the prior art. As is well appreciated by those skilled in the art, during a welding operation the welding electrode must be at a predetermined distance from the work surface. This distance is usually determined principally on the basis of the nature of the electrode, the workpiece, the intensity of the electric arc employed for the welding, and the nature of the desired weld.
- welding apparatus of the prior art In order to position the electrode at the desired predetermined distance from the work surface (set in advance by an operator), welding apparatus of the prior art usually employ a lead screw actuated mounting assembly or carriage for the electrode.
- the lead screw is rotated by an electric motor and, depending on the direction of rotation of the motor, a threaded sleeve mounted to the lead screw carries the electrode towards or away from the work surface.
- the electrical resistance or impedance between the electrode and the workpiece is monitored in the prior art.
- the electrode is considered to be at zero distance from the workpiece when the monitored resistance or impedance falls below a predetermined threshold value.
- an electronic control unit causes the electric motor to reverse to carry the electrode away from the workpiece to a predetermined distance.
- the welding arc is usually initiated when the electrode is disposed at the predetermined distance from the work surface.
- the above-summarized prior art welding apparatus should work reliably, in practice its operation is far from optimal.
- the principal cause for errors and unreliability of operation lies in the fact that a relatively large electric resistance or impedance may exist between the electrode and the workpiece in spite of the fact that the electrode physically touches the workpiece.
- a corroded, rusty, or otherwise coated or unclean metal surface of the workpiece may offer an electrical resistance or impedance which is significantly higher than the threshold value.
- the prior art welding apparatus does not "sense" that physical contact has been made between the electrode and the workpiece, and the motor driven lead screw assembly may continue to attempt to drive the electrode further into the workpiece. At the least, in the situation described above, the ability of the prior art welding apparatus for sensing contact between the electrode and the workpiece is seriously impaired.
- a welding power supply of low resistance is already connected to the electrode and the workpiece.
- the measured resistance or impedance between the electrode and the workpiece may fall below the threshold value even though the electrode does not physically contact the workpiece.
- welding apparatus including an electric motor and an electrode carrying assembly which is driven by the electric motor.
- the electrode carrying assembly carries the electrode either towards a workpiece or away from the workpiece, depending on the direction of rotation of the electric motor.
- the electrode carrying assembly is operatively associated with a mechanical sensing device including an electric switch, which is tripped substantially at the moment when, during movement of the electrode towards the workpiece, the electrode physically contacts the workpiece. Tripping off the switch reverses rotation of the electric motor to carry the electrode to a predetermined distance from the workpiece.
- FIG. 1 is a perspective view of a preferred embodiment of the improved welding apparatus of the present invention, however, parts of a mounting assembly whereto the apparatus is mounted are broken away in the view;
- FIG. 2 is a partial perspective view of a lead screw and sleeve assembly incorporated in the preferred embodiment
- FIG. 3 is a partial cross-section of the welding apparatus taken on lines 3,3 of FIG. 1, the view showing the welding apparatus in a first position wherein a welding electrode does not contact a workpiece;
- FIG. 4 is a partial cross-section of the welding apparatus showing the welding apparatus in a second position wherein the welding electrode contacts the work surface, the cross-section being analogous to the cross-section taken on lines 3,3 of FIG. 1;
- FIG. 5 is a cross-sectional view taken on lines 5,5 of FIG. 3;
- FIG. 6 is a cross-sectional view taken on lines 6,6 of FIG. 3;
- FIG. 7 is a partial side view showing the welding apparatus in the first position wherein the welding electrode does not contact the workpiece
- FIG. 8 is a partial side view showing the welding apparatus in the second position wherein the welding electrode contacts the workpiece.
- the welding apparatus 20 of the present invention is disclosed. It should be noted at the outset, that the welding apparatus 20 of the present invention incorporates certain features and components which are common with prior art welding apparatus. These features and components are described here only to the extent necessary to explain and illuminate the present invention.
- the principal function of the welding apparatus 20 is to mount a welding electrode 22, and to bring the electrode 22 into contact with a workpiece or work surface.
- the electrode 22 including a tube 24 supplying argon or like inert gas for the welding operation is only schematically shown on the drawing Figures.
- the argon supply tube 24 substantially envelopes the electrode 22 which is coaxially mounted substantially in the center of the tube 24.
- the workpiece or work surface is schematically shown on FIGS. 7 and 8 and bears the reference numeral 26.
- the electrode 22 After direct contact is made between the electrode 22 and the workpiece 26, the electrode 22 is withdrawn to a predetermined distance from the workpiece 26. An electric arc is initiated between the electrode 22 and the workpiece 26 when the electrode 22 has reached the predetermined distance from the workpiece 26.
- the contact of the electrode 22 with the workpiece 26 establishes a reference point for the measure of the predetermined distance. Therefore it is of great importance for the success of the welding operation to determine the time of contact reliably and accurately.
- the welding apparatus 20 of the present invention principally differs from prior art welding apparatus in the manner the contact of the electrode 22 with the workpiece 26 is sensed.
- the welding apparatus 20 is shown to include a housing 28 to which an electric motor 30 is mounted.
- the housing 28 is attached to a conventional welding apparatus mounting assembly which is not shown on the drawing Figures.
- the electric motor 30 has an output axle 32, shown on FIG. 6, the rotation of which is reversible.
- the electric motor 30 is a D.C. motor so that its rotation is reversible by reversing the polarity of a current supplying the motor 30.
- the electric motor 30 may also be a reversible A.C. motor, or any reversible motor.
- the output of the electric motor 30 is transmitted by a suitable timing belt 34 or the like, to a pulley 36 fixedly attached to a rotatable shaft 38 of a lead screw-threaded sleeve assembly 40.
- the lead screw-threaded sleeve assembly 40 is a device which moves the electrode 22 up or down depending on the direction of rotation of the output axle 32 of the electric motor 30. Stated differently, the lead screw-threaded sleeve assembly 40 converts the rotary motion of the electric motor 30 to lineal motion of the electrode 22 along the direction of the longitudinal axis of a lead screw 42.
- the lead screw-threaded sleeve assembly 40 is shown to include the lead screw 42, which has a substantially smooth portion 44 rotatably mounted in a suitable bearing 46.
- the bearing 46 is disposed in the housing 28.
- the pulley 36, driven by the timing belt 34, is disposed above the bearing 46.
- a locknut 48 is shown above the pulley 36 on the threaded upper end of the shaft 38 of the lead screw 42.
- the shaft 38 of the lead screw 42 is threaded below the bearing 46, and a sleeve 52 is threadedly mounted upon the shaft 38.
- a substantially cylindrical depression 56 is located on a lower surface 58 of the housing 28 around the area where the rotatable shaft 38 of the lead screw 42 exits from the bearing 46. This is shown on FIG. 2.
- a hollow cylindrical cover tube 60 is inserted into the depression 56, and is held therein in a fixed, nonrotatable manner by a plurality of lugs 62 which engage matching notches 64 in the tube 60.
- Four (4) rods 66 are mounted into the housing 28 to engage interior bosses 68 of the cover tube 60.
- a lower end 70 of the tube 60 rests on an additional lower piece 72 of the housing 28 which also receives the lower ends of rods 66.
- Conventional nuts 74 which affix the rods 66 to the lower housing piece 72 are shown on the side views of FIGS. 7 and 8.
- the threaded sleeve 52 incorporates a flange 76 which has appropriately positioned notches 78 to receive the rods 66 so that neither the cover tube 60, nor the lower housing piece 72, nor the sleeve 52 are capable of rotation relative to the housing 28.
- the lower housing piece 72 includes a circular aperture to allow the sleeve 52 to move longitudinally relative to the rigidly held lower housing piece 72.
- the interior (not shown) of the aperture of the housing piece 72 is lined with a low friction plastic bearing (not shown).
- a threaded bolt 80 is attached to the lowermost part of the sleeve 52. The purpose of the threaded bolt 80 is to permit mounting of the welding electrode 22 through a suitable mounting racket 82 and a nut 84.
- the lead screw-sleeve assembly 40 (or electric cylinder) of the present invention is "self-limiting" in its downward movement. In other words, it automatically discontinues downward movement of the sleeve 52 (and therefore of the electrode 22 as well) as soon as the electrode 22 encounters a physical obstruction (such as the workpiece 26) in its downward path.
- the smooth portion 44 of the shaft 38 of the lead screw 42 does not terminate immediately below the bearing 46. Instead, the smooth portion 44 continues for a predetermined, albeit short, distance below the bearing 46.
- a shoulder or flange 86 is provided on the shaft 38 where the smooth portion 44 ends and the threads of the shaft 38 begin.
- the shaft 38 is capable of a limited axial sliding movement relative to the bearing 46 or housing 28. As is apparent from FIG. 4, the shaft 38 is capable of moving upward relative to the bearing 46 until the shoulder 86 engages the bearing 46.
- a spring loaded cam follower rod 88 is shown disposed in the housing 28 with an end 90 resting in contact with an upper end 92 of the shaft 88.
- the cam follower rod 88 is capable of moving in an upwardly direction against its spring bias to follow the shaft 38 when the shaft 38 slides upwardly in the bearing 46.
- rotation of the cam follower rod 88 is prevented by a transversely disposed pin 93. This is respectively shown in FIGS. 3 and 4.
- An electric switch 94 preferably a microswitch, is fixedly mounted to the housing 28 to be disposed just above the protruding upper end 96 of the cam follower rod 88.
- the microswitch 94 is connected to an electronic control unit 98 which is schematically illustrated on FIG. 1.
- the function of the microswitch 94 is to send an appropriate electric signal to the control unit 98 when the microswitch 94 is tripped by the upwardly moving cam follower rod 88.
- Description of the structure of the control unit 98 is not deemed necessary here, since such a unit may be built in accordance with standard practice in the art to accomplish the hereinafter-detailed functions.
- a control unit 98 capable of accomplishing the hereinafter-detailed functions, particularly adapted for use in conjunction with the present invention, and having certain novel features as well, is described in a copending application for United States patent by the same inventor as the present application and assigned to the same assignee.
- the subject matter of the aforesaid copending application bearing attorney docket No. 1900 is hereby expressly incorporated by reference.
- the improved welding apparatus 20 of the present invention operates in the following manner.
- the electrode 22 is positioned remotely from the workpiece 26.
- the control unit 98 When an operator (not shown) desires to initiate the welding process, he activates (e.g., by pressing an appropriate button) the control unit 98.
- the control unit 98 energizes the electric motor 30 to rotate in an appropriate direction to drive the lead screw-sleeve assembly 40 and the electrode 22 therewith, towards the workpiece 26.
- the shaft 38 is usually gravity biased to occupy its first position shown on FIG. 3, wherein the shoulder 86 is disposed at the predetermined distance below the bearing 46.
- the first position of the shaft 38 corresponds to the position of the welding apparatus 20 shown on FIG. 7, wherein the electrode 22 is not in contact with the workpiece 28.
- the gravity bias of the shaft 38 to occupy its first position relative to the bearing 46 and relative to the microswitch 94 is further aided by the spring bias of the spring bearing cam rod 88.
- the spring 100 which biases the cam rod 88, may be made sufficiently strong to bias the shaft 38 into its first position even when not aided by gravity. This is necessary, for example, in a situation wherein the electrode 22 is moved in a substantially horizontal direction.
- the cam rod 88 is likewise pushed upward to trip the microswitch 94.
- the microswitch 94 is tripped substantially in the same instant when the electrode 22 physically contacts the workpiece 28. Tripping of the microswitch 94 sends an appropriate signal to the control unit 98 and establishes an important reference point for the further functioning of the control unit 98.
- the control unit 98 Upon receipt of the signal from the tripped microswitch 94, the control unit 98 causes the electric motor 30 to reverse rotation for a predetermined time period, thereby removing the electrode 22 a predetermined distance from the workpiece 26.
- the welding arc (not shown) is initiated by application of voltage only when the electrode reached the predetermined distance from the workpiece 26.
- the control unit 98 may be set to apply voltage to initiate the arc automatically.
- the control unit 98 may merely set the distance between the electrode 22 and the workpiece 26 in the above-described manner, and initiation of the arc may require further action (such as pressing of a button) by an operator (not shown).
- a principal advantage of the welding apparatus 20 of the present invention is that setting of the predetermined distance between the electrode 22 and the workpiece 26 is reliable and accurate. It is not disturbed or affected by commonly occurring variations in electrical resistance or impedance between the electrode 22 and the workpiece 26.
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- Mechanical Engineering (AREA)
- Resistance Welding (AREA)
Abstract
Description
Claims (21)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/372,193 US4439664A (en) | 1982-04-26 | 1982-04-26 | Welding apparatus wherein physical contact of welding electrode with workpiece is mechanically sensed |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/372,193 US4439664A (en) | 1982-04-26 | 1982-04-26 | Welding apparatus wherein physical contact of welding electrode with workpiece is mechanically sensed |
Publications (1)
Publication Number | Publication Date |
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US4439664A true US4439664A (en) | 1984-03-27 |
Family
ID=23467094
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US06/372,193 Expired - Fee Related US4439664A (en) | 1982-04-26 | 1982-04-26 | Welding apparatus wherein physical contact of welding electrode with workpiece is mechanically sensed |
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US (1) | US4439664A (en) |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5160821A (en) * | 1992-03-17 | 1992-11-03 | Esab Welding Products, Inc. | Mounting apparatus for a cutting torch |
US5187348A (en) * | 1991-10-30 | 1993-02-16 | Westinghouse Electric Corp. | Weld electrode-to-workpiece arc gap setting apparatus and method |
WO1996023618A1 (en) * | 1995-02-04 | 1996-08-08 | Anton Koukal | Driving device for the vertical adjustment of a gas cutting machine burner |
US6373020B1 (en) * | 1999-05-26 | 2002-04-16 | Takao Kinzoku Kogyo Co., Ltd. | Welding apparatus |
US6563084B1 (en) | 2001-08-10 | 2003-05-13 | Lincoln Global, Inc. | Probe for touch sensing |
US20100043244A1 (en) * | 2008-08-21 | 2010-02-25 | Messer Cutting Systems Inc. | Edge Detect System |
US20100325889A1 (en) * | 2009-06-24 | 2010-12-30 | David Buttress | Apparatus and method for joining solar receiver tubes |
US20110049106A1 (en) * | 2009-08-30 | 2011-03-03 | David Buttress | Apparatus and method for field welding solar receiver tubes |
US10717147B2 (en) * | 2005-12-30 | 2020-07-21 | Roger Hirsch | Resistance welding machine pinch point safety sensor |
US11458559B2 (en) | 2018-10-18 | 2022-10-04 | Dnv Gl Usa | Method and apparatus for arc welding by remote control |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
SU219039A1 (en) * | В. В. Смирнов, Ю. В. Фомин, В. И. Абрамов , О. Н. Породим | DEVICE FOR ARC WELDING | ||
US4284871A (en) * | 1978-11-11 | 1981-08-18 | Messer Griesheim | Automatic adjustment of the initial height of a flame cutter to a workpiece |
-
1982
- 1982-04-26 US US06/372,193 patent/US4439664A/en not_active Expired - Fee Related
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
SU219039A1 (en) * | В. В. Смирнов, Ю. В. Фомин, В. И. Абрамов , О. Н. Породим | DEVICE FOR ARC WELDING | ||
US4284871A (en) * | 1978-11-11 | 1981-08-18 | Messer Griesheim | Automatic adjustment of the initial height of a flame cutter to a workpiece |
Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5187348A (en) * | 1991-10-30 | 1993-02-16 | Westinghouse Electric Corp. | Weld electrode-to-workpiece arc gap setting apparatus and method |
US5160821A (en) * | 1992-03-17 | 1992-11-03 | Esab Welding Products, Inc. | Mounting apparatus for a cutting torch |
WO1996023618A1 (en) * | 1995-02-04 | 1996-08-08 | Anton Koukal | Driving device for the vertical adjustment of a gas cutting machine burner |
US6373020B1 (en) * | 1999-05-26 | 2002-04-16 | Takao Kinzoku Kogyo Co., Ltd. | Welding apparatus |
US6563084B1 (en) | 2001-08-10 | 2003-05-13 | Lincoln Global, Inc. | Probe for touch sensing |
US10717147B2 (en) * | 2005-12-30 | 2020-07-21 | Roger Hirsch | Resistance welding machine pinch point safety sensor |
US8006403B2 (en) * | 2008-08-21 | 2011-08-30 | Messer Cutting Systems Inc. | Edge detect system |
US20100043244A1 (en) * | 2008-08-21 | 2010-02-25 | Messer Cutting Systems Inc. | Edge Detect System |
US20100325889A1 (en) * | 2009-06-24 | 2010-12-30 | David Buttress | Apparatus and method for joining solar receiver tubes |
US9126290B2 (en) | 2009-06-24 | 2015-09-08 | David Buttress | Method for joining solar receiver tubes |
US8841573B2 (en) | 2009-08-30 | 2014-09-23 | David Buttress | Apparatus for field welding solar receiver tubes |
US20110049106A1 (en) * | 2009-08-30 | 2011-03-03 | David Buttress | Apparatus and method for field welding solar receiver tubes |
US11458559B2 (en) | 2018-10-18 | 2022-10-04 | Dnv Gl Usa | Method and apparatus for arc welding by remote control |
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AS | Assignment |
Owner name: RUSSELL, LARRY, 24882 ROLLINGWOOD RD. EL TORO, CA. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:TOOHEY, WILLIAM J.;REEL/FRAME:003997/0492 Effective date: 19820422 |
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Owner name: JETLINE ENGINEERING, INC, 16871 MILLIKEN, AVE, IRV Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:RUSSELL, LARRY;REEL/FRAME:004134/0818 Effective date: 19830518 |
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Owner name: ILLINOIS TOOL WORKS INC., ILLINOIS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:JETLINE ENGINEERING, INC.;REEL/FRAME:011149/0263 Effective date: 20000831 |
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